package com.fuhailiu.media.effect;

import android.opengl.GLES20;

public class GLToolbox {

	public static int loadShader(int shaderType, String source) {
		int shader = GLES20.glCreateShader(shaderType);
		if (shader != 0) {
			GLES20.glShaderSource(shader, source);
			GLES20.glCompileShader(shader);
			int[] compiled = new int[1];
			GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
			if (compiled[0] == 0) {
				String info = GLES20.glGetShaderInfoLog(shader);
				GLES20.glDeleteShader(shader);
				shader = 0;
				throw new RuntimeException("Could not compile shader " + shaderType + ":" + info);
			}
		}
		return shader;
	}

	public static int createProgram(String vertexSource, String fragmentSource) {
		int vertexShader = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
		if (vertexShader == 0) {
			return 0;
		}
		int pixelShader = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
		if (pixelShader == 0) {
			return 0;
		}

		int program = GLES20.glCreateProgram();
		if (program != 0) {
			GLES20.glAttachShader(program, vertexShader);
			checkGlError("glAttachShader");
			GLES20.glAttachShader(program, pixelShader);
			checkGlError("glAttachShader");
			GLES20.glLinkProgram(program);
			int[] linkStatus = new int[1];
			GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linkStatus, 0);
			if (linkStatus[0] != GLES20.GL_TRUE) {
				String info = GLES20.glGetProgramInfoLog(program);
				GLES20.glDeleteProgram(program);
				program = 0;
				throw new RuntimeException("Could not link program: " + info);
			}
		}
		return program;
	}

	public static void checkGlError(String op) {
		int error;
		while ((error = GLES20.glGetError()) != GLES20.GL_NO_ERROR) {
			throw new RuntimeException(op + ": glError " + error);
		}
	}

	public static void initTexParams() {
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MAG_FILTER, GLES20.GL_LINEAR);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_MIN_FILTER, GLES20.GL_LINEAR);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_S, GLES20.GL_CLAMP_TO_EDGE);
		GLES20.glTexParameteri(GLES20.GL_TEXTURE_2D, GLES20.GL_TEXTURE_WRAP_T, GLES20.GL_CLAMP_TO_EDGE);
	}

}
